Schedtool interfaces with the Linux CPU scheduler. It allows the user to set and query the CPU-affinity and nice-levels of processes, as well as all scheduling policies, like batch or real-time (RR/FIFO) classes and their priorities. It can be used to avoid skipping for A/V-applications, to lock processes onto certain CPUs on SMP/NUMA systems, or to adjust nice-levels of lesser important jobs to maintain a high amount of interactive responsiveness under high load. All special scheduling classes of the -ck kernel patchset are also supported. Certain modes (as of this writing: SCHED_IDLEPRIO and SCHED_ISO) need a patched kernel; see the INSTALL file for details.